Validate multiple thumbprint in the apim policy

We have multiple thumbprints to validate in the apim policy.So we decided to create a list variable to store all thumbprints and pass that variable to apim policy
Example : when condition=(!new list{thumbprints}.Contains(…).

But not able to assign the thumbprint values to the parameter,As i am new to this i might be doing something wrong in the code.Could you please share the sample of how we can assign the terraform list variable in apim policy